Process and device for winding up threads



June 23, 1970 BAUER ET AL 3,516,614

PROCESS AND DEVICE FOR WINDING UP THREADS Filed March 28, 1968 .4Sheets-Sheet 1 FIG. 1

INVENTORS GUNTHER BAUER JAKOB BUCHER H ATTORNEYS June 23, 1970 a. BAUERET AL 3,516,614

PROCESS AND DEVICE FOR WINDING UP THREADS Filed March 28, 1968 4Shoots-Shack :3

V 4 9 v M Q- hyperbole for L 1 hyperbole for L hyperbole for L INVENTORSGUNTHER BAUER JAKOB BUCHER 5 ATTORNEYS June 23, 1970 Q a u ET AL 3 516614 PROCESS AND DEVICE FOR WINDING UP THREADS Filed March 28, 1968 4Sheets-Sheet 3 INVENTORS HEW. ATTORNEYS June 23, 1970 BAUER ET AL3,516,614

I PROCESS AND DEVICE FOR WINDING UP THREADS Filed March 28, 1968 .4Shaots-8hoot 4 INVENTORS GUNTHER BAUER JAKOB BUCHER il ATTORNEYS UnitedStates Patent Int. Cl. B6511 54/02 US. Cl. 24218 5 Claims ABSTRACT OFTHE DISCLOSURE The present invention provides a process for winding up adrawn synthetic thread on a tube with a substantially constant tensionof the thread during the winding operation. During the winding operationthe length of the free thread between the point where it leaves theelement which brings about a traverse motion of the thread and the pointwhere it meets the bobbin does not change or changes only slightly.

The present invention relates to the winding up of threads with asubstantially constant winding tension.

It has been proposed to Wind up drawn synthetic threads on tubes drivenby a driving drum, the traverse motion of the thread being brought aboutby a split drum. It has also been proposed to bring about the traversemotion by traversing thread guides.

When bobbins are wound with the aid of suitable devices a uniformwinding tension is desirable during winding. A uniform winding tensionpromotes uniformity in the properties of the thread, for example, thedegree of shrinkage, dyestuif affinity and elastic modulus. Moreover, aconstant winding tension is favoured from the point of view of safety;if the tension is too low the thread often winds round the driving druminstead of building up the bobbin. When a thread is wound up a certainlength thereof is free between the point where the thread leaves thetraversing element, for example the outer surface of a split drum, andthe point Where it is wound on the bobbin. In this specification thislength of thread is referred to as the drag length. In the usual windingprocesses the drag length changes as the bobbin is built up, i.e. duringthe winding operation.

The present invention is based on the observation that the windingtension remains constant during winding when the drag length ismaintained constant. Absolute constancy of the drag length is preferred,but the Winding tension is still sufficiently constant when, duringwinding, the drag length increases by at most one quarter of its initiallength and decreases by at most one tenth of its initial length.

There are a number of diiferent methods which may be used to maintainthe drag length substantially constant, the method suitable for anyparticular type of winding equipment depending, for example, on the typeof traversing element used, the relative sizes of various parts of thewinding equipment and the method used for driving the bobbin.

FIGS. 1-4 are schematic illustrations of various arrangementsexemplifying the principles of this invention.

It has been found, for example, that when a split drum is used astraversing element the drag length and, thus, the winding tension may bemaintained constant if the path followed by the centre of the bobbinduring the winding operation represents a hyperbola which can beconstructed point by point. The construction of such a ice hyperbolawill now be described with reference to FIG. 1 of the accompanyingdrawings. FIG. 1 shows, diagrammatically, a thread being wound on abobbin 1 driven by a driving drum 2 with traverse motion of a thread 3brought about by a split drum 4.

Referring to the drawings:

1M is the centre of the bobbin 1 R is the respective radius of thebobbin 1 M, is the centre of the driving drum 2 R, is the radius of thedriving drum 2 M is the centre of the split drum 4 R is the inner radiusof the split drum 4 and R is the outer radius of the split drum 4 Thethread 3 leaves the circle drawn round M at a distance R at B and leavesthe split drum at D. The thread 3 meets the bobbin at E. The distancebetween points D and E corresponds to the free length of the thread,i.e. the drag length L which, according to the present invention, shouldbe maintained constant. With an increasing diameter of the bobbin duringwinding the position of its centre changes. For each possible radius ofthe bobbin R the position of the centre of the bobbin M is theintersection of two circles drawn round M, and M so that if the radii ofthese circles are known for any given value of R the position of M canbe found. The radius of the circle round M, is equal to the sum of theradius of the driving drum R, plus the respective radius of the bobbinR,,,. The radius of the circle round M, is the hypotenuse of aright-angled triangle between points M C and M which can be constructedfor any position of the points B, D and B.

One short side of the triangle M,CM is formed by the sum of the innerradius of the split drum R (M B) plus the respective radius of thebobbin R (distance EM =distance BC) and the other short side of thetriangle is formed by the distance between point B and point D plus thedrag length 1,,(DE), (distance CM -=distance BE). The triangle M BD iscongruent for each position of D on the outer circumference of the splitdrum because the inner radius R and the outer radius R are constant andthe right angle between the thread 3 and the inner radius of the splitdrum R is always maintained at B. BD is therefore constant and as,according to the present invention, L is to be maintained constant, theshort side CM of the triangle M CM is constant during the whole windingoperation. The other short side M C (=R -l-R of the triangle M CM variesduring winding because of the change in the radius of the bobbin R Forany given value of R it is possible to calculate Rg-l-R and thehypotenuse of the triangle M CM so it is therefore possible to calcuatethe position of M for any value of R It is found that, for L to bemaintained constant, the centre of the bobbin M should describe a path 5which is part of a hyperbola (unless R =R see below).

Although winding up while maintaining the drag length L, constant ispreferred according to the present invention, it has been found thatthreads having uniform properties can be obtained with suflicient safetyof operation when, during the winding operation, the drag length L,increases by at most one quarter of its initial value and decreases byat most one tenth of its initial value.

With the use of the afore-described construction and considering themaximum and minimum values of the drag length a range can be determinedwithin which the path described by the centre of the bobbin during thewinding operation must be situated according to the process of theinvention. This is shown in FIG. 2. If the initial drag length L is tobe maintained constant, the

Patented June 23, 1970 centre of the bobbin must describe a hyperbolicorbit from M to M (hyperbola for L while the radius of the bobbinincreases from R to R When during the winding operation an increase byone quarter of the initial length of the drag length is tolerated, theuse of the value 4 L gives a hyperbolic orbit which is shown on FIG. 2below the hyperbola for L whereas a shortening of the free drag length Lby one tenth of the initial length to L gives the upper hyperbola(hyperbola for L According to the invention the path of the centre ofthe bobbin M during the winding operation must be situated within thezone limited by the two outer hyperbolas.

The process of the invention is easy to carry out on an industrial scalebecause numerous devices can be used for guiding the centre of thebobbin on a path as stipulated by the conditions specified above.

To carry out the process of the invention it is possible, for example,to use a device comprising a split drum for giving traverse motion tothe thread, a driving drum and a tube set on a bobbin holder. The bobbinbuilt up on the tube is driven by the driving drum. The bobbin holder isfitted in a known manner on a swingable lever. The length of the leverand the position of its point of rotation are chosen in such a mannerthat the circle described by the centre of the bobbin during the windingoperation substantially approaches the optimum hyperbolic orbit for theinitial drag length used and is situated within the zone limited by thetwo outer hyperbolas. The length of the lever arm and the position ofits point of rotation can be readily determined from three points of theoptimum hyperbolic orbit by construction of the circle described by thecentre of the bobbin as the point of intersection of two lines, eachline perpendicularly bisecting a chord drawn between two of the threepoints chosen.

Alternatively, the process of the invention can be carried out with adevice in which the movable bobbin holder is fitted on a swingable levereccentrically supported in known manner or by any other means suitablefor guidance along the required path.

According to a further preferred embodiment of the process of theinvention a constant drag length L and a constant winding tension may bemaintained by guiding the centre of the bobbin M on a straight line.This method of maintaining a constant drag length may be used when theinner radius of the split drum R and the radius of the driving drum Rare equal. This is shown on FIG. 3. The straight line representing thecourse of the centre of the bobbin M is perpendicular to the linebetween the centres of the driving drum M, and the split drum M With theuse of known equipment it is very easy to guide the centre of the bobbinon a straight line.

The process of the invention can also be carried out with known devicesin which with an increasing diameter of the bobbin the bobbin is notmoved away from the driving drum but the driving drum is moved while theaxis of the bobbin remains in a constant position. With a device of thistype the driving drum can only drive those bobbins which startsimultaneously winding the thread. With this mode of execution theconditions stipulated above must be suitably adapted. Other devices canalso be used to carry out the process of the invention, for example adevice in which the bobbin is directly driven by a split drum withomission of the driving drum.

It is quite obvious that devices may also be used for the process of theinvention in which the traverse motion of the thread is brought about bya traversing thread guide (oscillatable thread guide). Such a mode ofexecution of the process is illustrated in FIG. 4. If the thread is tobe wound up with constant drag length the appropriate path of the centreof the bobbin M is a straight line 7 which is perpendicular to theprojected direction of the thread as it leaves the thread guide 6, thepoint of intersection E of the line 7 with the centre line of the thread3 being below the traversing thread guide 6 by the distance DE=L In thiscase D is the point where the thread leaves the traversing thread guide(which corresponds to the point where the thread leaves the split drum).Thus, when the arrangement shown in FIG. 4 is used, a constant draglength can be obtained by guiding the centre of the bobbin M on astraight line.

Since, according to the invention, a change of the drag length L duringthe winding operation by an increase of A of the initial drag length anda decrease by of the initial drag length is allowed, a zone isestablished between a straight line 8 (see FIG. 4), which is by thedistance W L below the thread guide 6, and a straight line 9, which isby the distance L below the thread guide 6. The path of the centre ofthe bobbin should be situated within this zone. When the centre of thebobbin M describes an arc of a circle, i.e. with the use of a swingablelever, the radius and the centre of the circle can be determined in themanner described above. The extreme case of such a circular path is apath 10 of the centre of the bobbin M marked in FIG. 4. With this path,winding of the bobbin starts at the intersection of the straight line 7(which is below the traversing thread guide by the distance L with acircle round M having the radius R +R In its culmination point thecircular path 10 touches the straight line 8 situated below thetraversing thread guide 6 at a distance L It ends in the intersection ofthe straight line 9 (which is situated below traversing thread guide 6at the distance L with a circle round M having the radius R +R A circlecomplying with these conditions has the radius R.

What is claimed is:

1. A process for winding up a drawn synthetic thread on a tube withtraverse motion of the thread and driving of the building bobbin with adriving drum, with substantially constant winding tension, wherein,during winding, the length of the free thread between the point where itleaves the traversing element and the point where it meets the bobbinincreases by at most one quarter of its initial value and decreases byat most one tenth of its initial value, and wherein the traverse motionof the thread is brought about by a split drum and the centre of thebobbin is guided on a path situated between two hyperbolas which areconstructed point by point with an increasing radius of the bobbin asintersection of two circles, one circle drawn round the centre of thedriving drum with a radius corresponding to the sum of the radius of thedriving drum plus the respective radius of the bobbin, the other circledrawn round the centre of the split drum with a radius equal to thehypotenuse of a right-angled triangle, one short side of which is formedby the sum of the inner radius of the split drum plus the respectiveradius of the bobbin and the other short side of which is formed by thesum of the length of the inner radius of the split drum plus therespective radius of the bobbin and the other short side of which isformed by the sum of the length of the thread between the point where itleaves the inner circle of the split drum and the point where it leavesthe split drum plus the length of the free thread between the pointwhere it leaves the split drum and the point where it meets the bobbin,for the construction of the one hyperbola the length of the free threadbeing 7 of its initial value and for the construction of the otherhyperbola the length of the free thread being W of its initial value.

2. The. process for winding up a drawn synthetic thread on a tube withtraverse motion of the thread and driving of the building bobbin with adriving drum, with substantially constant winding tension, wherein,during winding, the length of the free thread between the point where itleaves the traversing element and the point where it meets the bobbinincreases by at most one quarter of its initial value and decreases byat most one tenth of its initial value during winding, wherein thetraverse motion of the thread is brought about by a split drum and thecentre of the bobbin is guided on a path which is constructed point bypoint with increasing radius of the bobbin as intersection of twocircles, one drawn round the centre of the driving drum with a radiuscorresponding to the sum of the radius of the driving drum plus therespective radius of the bobbin, and the other circle drawn round thecentre of the split drum with a radius that is equal to the hypotenuseof a right-angled triangle, one short side of which is formed by the sumof the inner radius of the split drum plus the respective radius of thebobbin and the other short side of which is formed by the distance,which is maintained constant during winding, between the point where thethread leaves the inner circle of the split drum and the point where itmeets the bobbin.

3. A device for winding up a drawn synthetic thread on a tube withtraverse motion of the thread and driving of the building bobbin with adriving drum, with substantially constant winding tension, wherein,during winding, the length of the free thread between the point where itleaves the traversing element and the point where it meets the bobbinincreases by at most one quarter of its initial value and decreases byat most one tenth of its initial value, comprising a split drum to bringabout a traverse motion of the thread, a supported bobbin holder movablymounted on a' swingable lever with a tube, and a driving drum to drivethe bobbin, wherein means are provided to guide the centre of the bobbinduring winding on a path situated between two hyperbolas constructedpoint by point with increasing radius of the bobbin as intersection oftwo circles, one circle drawn round the centre of the driving drum witha radius corresponding to the sum of the radius of the driving drum plusthe respective radius of the bobbin, the other circle drawn round thecentre of the split drum with a radius that is equal to the hypotenuseof a right-angled triangle one short side of which is formed by the sumof the inner radius of the split drum plus the respective radius of thebobbin and the other short side of which is formed by the sum of thelength of the thread between the point where it leaves the inner circleof the split drum and the point where it leaves the split drum plus thelength of the free thread between the point where it leaves the splitdrum and the point where it meets the bobbin, for the construction ofthe one hyperbola the length of the free thread being A of the initiallength thereof and for the construction of the other hyperbola thelength of the free thread being W of the initial length thereof.

4. A device for winding up a drawn synthetic thread on a tube withtraverse motion of the thread and driving of the building bobbin with adriving drum, with substan tially constant winding tension, wherein,during winding, the length of the free thread between the point where itleaves the traversing element and the point where it meets the bobbinincreases by at most one quarter of its initial value and decreases byat most one tenth of its initial value during winding, comprising asplit drum to bring about a traverse motion of the thread, a movablysupported bobbin holder with tube and a driving drum to drive thebobbin, wherein means are provided to guide the centre of the bobbinduring winding on a path which is constructed point by point withincreasing radius of the bobbin as intersection of two circles, onedrawn round the centre of the driving drum with a radius correspondingto the sum of the radius of the driving drum plus the respective radiusof the bobbin, the other circle drawn round the centre of the split drumwith a radius that is equal to the hypotenuse of a right-angledtriangle, one short side of which is formed by the sum of the innerradius of the split drum plus the respective radius of the bobbin andthe other short side of which is formed by the distance, which isconstant during winding, between the point where the thread leaves theinner circle of the split drum and the point where it meets the bobbin.

5. A device as set forth in claim 3 wherein the bobbin holder is mountedon the swingable lever, the length of the lever and the position of itspoint of rotation being determined from three points of the optimumhyperbola by construction of the circle described by the centre of thebobbin as the point of intersection of two lines, each lineperpendicularly bisecting a chord drawn between two of the three pointschosen.

References Cited UNITED STATES PATENTS 2,752,100 6/ 1956 Strange.2,811,317 10/1957 Herbert et al. 3,008,658 11/1961 Akers. 3,009,66111/1961 Akers.

NATHAN L. MINTZ, Primary Examiner UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Patent No. 3,51 6,61 14. Dated June 23, 1 970Gunther Bauer and Jakob Bucher Inventor(s) It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

Column 1 lines 55-57, delete "inner length of the" SELED JAN 5 1971Atteat:

Edward M. Flmhm J Aucsting Officer mm 3, A: 33.

Gollnisaioner of Patents FORM PO-IOSO (0-69) USCOMNPDC 5037mm n u 5GOVERNMENT rammm ornc: In: o-scs-ua

